MURIDAH—SIGMODONTES—NEOTOMA MAGISTER. 29 
tawny Nebraska ones. Professor Baird, with no examples of Arctic Neotoma 
(the original drummondii) betore him, saw the differences between the short- 
tailed ones Richardson described and the long-tailed ones given by Audubon 
as “‘drummondii”; and then receiving two short-tailed ones from Nebraska 
(Suckley’s and Hayden’s first skins), he concluded that these must be the 
real drummondii, and adopted Cooper’s name occidentalis for the Washington 
and Oregon series. The bright colors and soft fur of the Nebraskan ones, 
really somewhat different from the darker and harsher pelage of the others, 
confirmed his erroneous impression. But those who may-desire to push spe- 
cific differentiation further than we are willing to, must recognize ¢hree species 
as above indicated, or else indorse the view that there is but one. 
NEOTOMA MAGISTER, Baird. 
Fossil Neotoma. 
Neotoma magister, Barrp, M. N. A. 1857, 498 (in text).—Coves, Proc. Acad. Nat. Sci. Phila. 1874, 175. 
Locality of remains.—Caves of Pennsylvania, near Harrisburg and 
Carlisle. 
This species is based upon a number of under jaws gathered in the 
above-mentioned places. These differ from the same bones of the existing 
species in averaging rather larger; but the difference is not decided. Thus, 
No. 12207 is precisely the size of No. 6883 (NV. cinerea). ‘The teeth show 
no appreciable peculiarities: we have them in various stages of wear, all 
of which can be matched in our series of recent specimens; and the same is 
true of the shape of the several parts of the jaw. As far as these fragment- 
ary witnesses go, we cannot determine JV. magister to be anything more than 
a former condition of one of the existing species—probably floridana ; but 
as we have it separated by a considerable lapse of time, and have no assur- 
ance that it was not quite different in color, or in the proportions of the 
limbs, ears, tail, &c., the expediency of retaining the name is_evident. 
With this case in hand, we offer an hypothesis that is none the less rea- 
sonable for being presumptive. Neotoma magister was the original species at 
the time the genus was differentiated from the then coéxistent types of 
Murines, and became the progenitor of the four kmds (“‘species”) of Neotoma 
living in America to-day. Those individuals that remained at and about the 
locality-of the parent stock have varied the least, and present the assem- 
blage of characters we call N. “floridana”. Other individuals, migrating 
westward, met, in the regions now known as Colorado, Kansas, &c., physicat 
